Shutter operating mechanism



July 7, 1 5 G, A. WILSON 2,894,085

SHUTTER OPERATING MECHANISM Filed Dec. 17, 1957 3 Sheets-Sheet l I 6% M M .llllllll llllllll INVENTOR. M 550/765 A. W/zJW/ W B h,

July 7, 1959 G. A. WILSON ,894,085

SHUTTER OPERATING MECHANISM Filed Dec. 17, 1957 5 Sheets-Sheet 2 l" in INVENTOR. 4504.4; 4. W/lJfl/V July 7, 1959 G. A. WILSON 2,894,085

SHUTTER OPERATING MECHANISM Filed Dec. 17, 1957 3 Sheets-Sheet 3 4 8.9 EzE=5. /6

I INVENTOR. A GEU/Ffd W/J'J United States SHUTTER OPERATING MECHANISM George A. Wilson, Media, Pa, assignor to I-T-E lircuit Breaker Company, Philadelphia, Pa, a corporation of Pennsylvania Application December 17, 1957, Serial No. 7633,3ti4

3 Claims. (Cl. Him-h) My invention relates to a shutter operating mechanism for circuit breakers and more specifically to a shutter mechanism which requires a minimum circuit breaker motion from its test position for shutter operation,

In metal clad switchgear, the rear of the cubicle is adapted to have stationary disconnect contacts which co-- operate with the cooperating disconnect contacts carried by the circuit breaker. When the cooperating disconnect contacts are not engaged, it is desirable that the stationary disconnect contacts be shielded from the movable disconnect contacts by a dielectric barrier in order to prevent accidental contact with the stationary contacts by maintenance personnel working in the cubicle, and further to increase the dielectric strength between the cooperating disconnect contacts when the circuit breaker is in the test position.

For this reason, a shutter mechanism is provided which normally comprises a dielectric plate having apertures therein. The plate has openings therein which move into registry with the cooperating disconnect contacts when the circuit breaker is moved into the operating position where the disconnect contacts are engaged. When the disconnect contacts are not engaged however, the apertures are not aligned with the contacts whereby a dielectric barrier is positioned between them.

In the past, the mechanism for operating the shutter was comprised of operating arms actuated by pins fixed to the circuit breaker frame. As a result, the circuit breaker has to be moved a relatively large longitudinal distance toward the operating position to enable the pins to cam the shutter operating arms upward and open the shutters. This preliminary travel distance of the breaker before the shutters are fully open causes wasted space in the depth of the cubicle.

The principle of my invention is to operate the shutter from a camming mechanism operated by the racking mechanism and independently of the longitudinal motion of the circuit breaker. That is to say, I utilize the relatively large rotational motion of the racking mechanism which corresponds to a relatively small longitudinal circuit breaker displacement for operating the shutter. Thus, substantially no additional depth need be added to the cubicle for allowing shutter operation.

Accordingly, a primary object of my invention is to provide a novel shutter operating mechanism which is operable responsive to a minimum longitudinal displace ment of the circuit breaker.

Another object of my invention is to provide a novel shutter operating mechanism which is operated from the motion of the racking mechanism.

A further object of my invention is to provide a novel operating mechanism which is operative responsive to a minimum motion of the circuit breaker from its test position,

These and other objects of my invention wiil become apparent from the following description when taken in conjunction with the drawings in which:

Figure 1 shows a typical circuit breaker prior to its entrance in its cubicle.

Figure 2 shows the breaker of Figure 1 prior to its entrance to the test position.

2,894,085 Fatented July 7, 1959 Figure 3 shows the breaker of Figure 1 after its entrance in the operating position.

Figure 4 shows a perspective View of my novel invention as applied to the device of Figures 1, 2 and 3.

Figure 5 is a partial side View of Figure 4, illustrating the shutter mechanism with the breaker in the test position, and the shutter closed.

Figure 6 is similar to Figure 5 where the circuit breaker is being moved from its test to its operating position, and the shutter is open.

Figure 7 is similar to Figure 6 and shows the mechanism with the circuit breaker in the operating position.

Referring now to Figures 1 through 3 which set forth the metal clad switchgear unit which is fully described in copending application, Serial No. 629,391, filed December 19, 1956, Patent No. 2,840,653, issued June 24, 1958, and assigned to the assignee of the instant application, a circuit breaker is shown as being movable into and out of a cubicle having a side wall 12, and a rear wall 14. The cubicle of course completely encloses the circuit breaker it) when it is moved into the cubicle.

As may be best seen in Figure 4, the rear cubicle wall M has apertures 16, 18, 2t), 22,, 24 and 26 therein which are aligned with stationary disconnect contacts 28, 30, 32, 34, 36 and 3S respectively. The stationary disconnects are of the type which accept cooperating movable contacts in plug-in engagement and are well known in the art.

Each of the stationary disconnect contacts cooperate with a respective disconnect contact carried by circuit breaker 1111. Thus, as seen in Figures 1 through 3, circuit breaker disconnect contacts 40 and 43-2 cooperate with stationary disconnects 2S and 38 respectively. Clearly, stationary disconnects 30, 32, 34 and 36 cooperate with similar circuit breaker disconnects (not shown) carried by circuit breaker 16 As fully described in above noted copending application, Serial No. 629,391, circuit breaker 10 carries a racking mechanism which includes a racking disk fastened to shaft 46 (Figure 4), which is terminated by arm 48, which in turn carries a protruding member 50.

The cubicle wall 12 as seen in Figures 1 through 4 carries a pair of guide members 52 and 54 which define a vertical slot extending from the cubicle wall 12 to act as a carnming means for racking the circuit breaker 10 between its test and operating position.

When circuit breaker 11b is moved from the position of Figure 1 to the position of Figure 2, wheel 59 engages the underside of the longitudinal extension of guide member 5d. Wheel 5%? is maintained in engagement with this underside by biasing means (not shown) which biases arm 48 in a clockwise direction in Figure 1. Therefore, as circuit breaker 1% is wheeled from the position of Figure 1 to the position of Figure 2, the member 50 will ride against the underside of guide 5 When the member 5t) reaches the dotted position of Figure 2, it will move into the bottom of the cam slot defined by members 52 and 54 by the above noted biasing means, and the breaker in will be in its test position.

In order to rack circuit breaker 10 from the test position of Figure 2 to the operating position of Figure 3, a racking lever .174 is inserted into apertures (not shown) in the racking disk 44, and the racking disk 44 is rotated in a clockwise direction in Figure 2. This rotation will cause the member 50 to ride up the carnming slot and therefore draws the circuit breaker 10 into the operating position of Figure 3. Clearly, the circuit breaker 10 can be withdrawn from the operating position by a counter-clockwise rotation of racking disk 44.

Figures 4, 5, 6 and 7 specifically show a shutter 60 having apertures 62, 64, 66, 68, 70 and 72 therein which are movable into registry with apertures 16, 18, 20, 22, 24 and 26 respectively of rear wall 14 when the barrier 60 is moved upwardly. More specifically, barrier 60 is slidably mounted with respect to rear wall 14 in any manner. For purposes of illustration, Figure 4 shows barrier 60 slidably mounted within U-shaped rails 74 and another rail on the other side of barrier 60 (not shown), the rails being rigidly mounted with respect to back wall 14.

The operating mechanism for operating shutter 60 includes L-shaped arm 76 which is pivotally mounted to side wall 12 at pivot 78. The front end of arm 76 extends through an aperture in member 52 and its cam shaped end 80 extends into the slot formed by members 52 and 54. The other end of arm 76 is pivotally connected to shutter pushrod 82 which has its other end pivotally connected to ear 84 fastened to shutter 60. A stop member 86 prevents rotation of arm 76 beyond a predetermined point which corresponds to the normally closed position of the shutter.

The operation of my novel shutter is as follows, particular reference being made to Figures 5, 6 and 7. When the circuit breaker is in the fully withdrawn or in the test position of Figures 1, 2 and 5, it is desired that the shutter 60 close off apertures 16 through 26 in wall 14 thus isolating the stationary disconnect contacts. Accordingly, in this position, the force of gravity operates on shutter 60 and drives arm 78 against stop 86 as seen in Figure 5.

When the breaker is racked from the test position to the operating position, it is necessary to lift the shutter by bringing apertures 16 through 26 into registery with apertures 62 through 72 respectively. Furthermore, it is desirable that the requirement of opening the shutter does not increase the length of travel required of the breaker in moving from test to operating position.

Accordingly, when moving from the position of Figure to the position of Figure 6, racking disk shaft 46 is rotated clockwise to cause member 50 to move up the racking slot. As member 50 moves upwardly, it engages cam surface 80 of arm 76 to thereby rotate arm 76 clockwiseabout pivot 78. This drives shutter pushrod 82, and the shutter 60 upward until the apertures in the shutter 60 register with the apertures in rear wall 14.

As racking disk shaft 46 continues to rotate, member 50 moves within the slot and continuously engages surface 84 of arm 76 to thereby continue to maintain the shutter open until the breaker is in the operating position of Figure 3.

The shutter further remains open when the breaker is racked out to the test position, until, as seen in Figure 5, the member 50 clears the cammed surface 80 and the shutter drops to its closed position.

It is to be noted that my novel structure operates shutter 60 independently of the forwardv motion of breaker 10, the input motion being derived from the substantial motion of the arm 48 of racking disk shaft 46. Thus, no additional cubicle depth is required in my novel structure to operate the shutter from the longitudinal motion of the circuit breaker.

In the foregoing, I have described my invention only in connection with preferred embodiments thereof. Many variations and modifications of the principles of my invention within the scope of the description herein are obvious. Accordingly, I prefer to be bound not by the specific disclosure herein but only by the appending claims.

I claim:

1. A shutter operating mechanism for a cubicle having a circuit breaker movable therein; said cubicle having a stationary disconnect contact mounted with respect thereto, said circuit breaker having a disconnect contact for cooperating with said stationary contact; a shutter of dielectric material normally interposed between said cooperating, disconnect contacts when said cooperatingcontacts are disengaged, said shutter being movable to expose said stationary disconnect contact to said circuit breaker disconnect contact when said circuit breaker and said circuit breaker disconnect contact is moved toward the engaged position; racking means for moving said circuit breaker toward said engaged position; said shutter operating mechanism being operatively connected between said shutter and said racking mechanism; said shutter operating mechanism converting the motion of said racking mechanism into a motion to move said shutter from said interposed position to said exposing position, said shutter being operated independently of the forward motion of said circuit breaker; said circuit breaker racking mechanism including a protruding rotatable member carried by said circuit breaker engageable with a stationary slot carried by said cubicle; said shutter operating mechanism including a member normally extending into said stationary slot; said member being cammed out of said slot when said protruding rotatable member engages said slot to operate said shutter to said exposing position.

2. A shutter operating mechanism for the shutter of a switchgear cubicle, said shutter operating mechanism being operatively connected to the racking mechanism of a circuit breaker positioned within said cubicle, said shutter normally closing off stationary disconnect contacts within said switchgear cubicle, said shutter being operated to a stationary disconnect contact exposing position responsive to operation of said circuit breaker racking mechanism to rack said circuit breaker to an operating position; said circuit breaker racking mechanism including a protruding rotatable member carried by said circuit breaker engageable with a stationary slot carried by said cubicle; said shutter operating mechanism including a member normally extending into said stationary slot; said member being cammed out of said slot when said protruding rotatable member engages said slot to operate said shutter to said exposing position.

3. In combination, a circuit breaker, a cubicle for mounting said circuit breaker, and a shutter means; saidcircuit breaker carrying a first disconnect contact, said cubicle carrying a second disconnect contact for cooperating with said first disconnect contact; said circuit breaker being movable within said cubicle to move said first disconnect contact into and out of engagement with said second disconnect contact; a racking mechanism for moving said circuit breaker within said cubicle; said racking mechanism including an externally operable shaft carried by said circuit breaker being terminated by an axially displaced extending member; said cubicle including' a slot means for receiving said axially displaced extending member whereby said circuit breaker is longitudinally moved responsive to rotation of said axially displaced member; a connecting mechanism for said shutter means; said connecting mechanism having one end operatively connected to said shutter means and another end forming a cam surface and extending into said slot means; said shutter means being movable between a position interposed between said first and second disconnect contacts and a removed position; said shutter being in said interposed position When said first and second disconnect contacts are in their disengaged position; operation of said first and second disconnect contacts to their said engaged position by operation of said racking mechanism causing said axially displaced member to engage said cam surface in said end of said connecting mechanism extending in said slot means and camming said last mentioned end out of its path; motion of said last mentioned end of said connecting mechanism movingsaid shutter means to its said removed position.

References Cited in the file of this patent UNITED STATES PATENTS 1,729,864 Brown Oct. 21-, 1929 2,673,260 Lester et al. Mar. 23, 1954 2,766,342 Johnson Oct. 9, I956 

